Entry 3 senses · 3 variants Webster, 1913 Glum /(glŭm)/ · IPA /ɡlʌm/ n. a. v. i. 01 n. Sullenness. 1. Sullenness.[Obs.] 02 a. Moody; silent; sullen. 1. Moody; silent; sullen. “I frighten people by my glun face.” — Thackeray. 03 v. i. To look sullen; to be of a sour countenance; to be glum. 1. To look sullen; to be of a sour countenance; to be glum.[Obs.]